Towards clarification of the inhibitory mechanism of wheat bran leachate on Microcystis aeruginosa NIES-843 (cyanobacteria): physiological responses

Abstract

Wheat bran leachate (WBL) has been shown to have an inhibitory effect on Microcystis aeruginosa in this study. In order to explore the inhibitory mechanism of WBL on M. aeruginosa, physiological responses of M. aeruginosa NIES-843 under the WBL stress were studied. The expressions of six important genes related to the D1 protein of photosynthetic processes (psbA), synthesis of microcystins (mcyB), antioxidant protein peroxiredoxin (prx), synthesis of fatty acid (fabZ) and the repair of biological macromolecules (recA, grpE) were studied. Under the WBL stress, no significant change was found in expressions of both grpE and recA, but expressions of psbA, fabZ and prx were shown to be down-regulated, and slight up-regulated expression was found in mcyB. It was shown that oxygen evolution of M. aeruginosa NIES-843 was significantly depressed, and intracellular ATP contents became lower, after exposure to WBL. Similarly, maximum electron transport rates of photosynthetic activities decreased significantly, but intracellular reactive oxygen species levels boosted dramatically under the WBL stress, and cell lysis was observed. Therefore, it is suggested that photosynthetic systems and membranes were the potential targets of toxicity of WBL on M. aeruginosa, and the oxidative damage is an important mechanism explaining the inhibitory effect of WBL on M. aeruginosa.

Physiological Responses of a Diazotrophic Cyanobacterium to Acidification of Paddy Floodwater: N2 Fixation, Photosynthesis, and Oxidative–Antioxidative Characteristics

“…Activities of respiration and photosynthesis could reflect the vitality of microorganisms [ 25 , 26 ]. The respiration rate of YYLX235 in the acidified treatments (pH 6.0–4.0) was far lower than the neutral control, indicating that the acidification of paddy floodwater decreased cell vitality of this diazotrophic cyanobacterium.…”

Algicidal Molecular Mechanism and Toxicological Degradation of Microcystis aeruginosa by White-Rot Fungi

“…Most of the microbial algae control technologies developed to date rely on algae-lysing bacteria [ 6 , 7 , 8 ], and the existing studies [ 9 , 10 , 11 ] have indicated that the Phanerochaete chrysosporium which control algae may be great in promoting the control of eutrophication by microbial methods. With the development of molecular biology, the molecular mechanism of the life activities of cyanobacteria and Microcystis aeruginosa has attracted people’s attention [ 12 , 13 , 14 , 15 ]. In recent years, the mechanisms involved in synthesizing various substances in M. aeruginosa cells [ 16 , 17 ], especially the molecular mechanisms that inhibit the growth of M. aeruginosa , have focused on biological rhythms, toxin synthesis, phycobiliprotein synthesis and its regulation, ATP synthetase [ 18 , 19 , 20 , 21 ], and the molecular response mechanisms through which algae removal technology affects the life activities of cyanobacteria, such as the regulation and expression of biorhythms and the regulation of algal toxin synthesis, have attracted increasing attention [ 22 , 23 , 24 ].…”